top of page

L'Apéro de L'Appart "Double A"

Public·9 membres

The Hot Day And Night Simpsons J

So Mitchell finds herself tossing and turning in bed, head spinning about trying to get her grandfather in the ground. She normally crashes at 8:30 or 9 at night, then wakes up at 4:30 a.m. for the day, even when school is out. But lately, she sleeps when she can, and even then she feels like she has barbed wire in her stomach.

The Hot Day And Night Simpsons J

For two hours on this night, she tries to sleep but keeps pulling out her phone. By 10:40 p.m., Simpson is typing a tweet she hoped she would never have to send. But she feels like she is out of options.

His wife, Linda, died in 1999. Their six older kids were all out of the house, but Jerry was suddenly raising Tara, 11, at the time, on his own. He could be more closed off than she would have liked, and then he'd come home exhausted from work. Tara says he'd wind down some nights with a little more alcohol than she would have liked. "He took care of me," she says. "I always ate. I always had food on the table."

To fulfill his dying wish, the total cost was about $18,000. By July 20, Jennifer and Tara, a niece and her aunt, both felt like they had maxed out what they could raise on their own. Simpson finally buckled that night and put up her treasured Watt gear for sale.

The ugly Twitter replies began to pile up overnight. One faction gently questioned her story, wanting further verification that the story was real. A Twitter user who donated money posted that he'd called the funeral home and gotten confirmation that her story checked out. She was fine with that level of prodding to make sure she was telling the truth.

Urban areas modify their local climate by altering the surface energy balance (Oke 1982; Arnfield 2003; Bohnenstengel et al. 2011). The convoluted form of urban surface areas (i.e., street canyons), results in a larger surface area in contact with the atmosphere, leading to additional absorption, reflection and emission of radiation, and turbulent flux exchanges compared to a planar area. The impact of street canyons can result in a lower effective albedo at canyon top than the urban surface material albedo. Usually, the effective albedo of a canyon is reduced compared to a planar surface with similar material properties and albedo leading to more effective absorption of radiation (direct and diffuse) during daytime (Masson 2000; Oke et al. 2017). During the night, a reduction in the efficiency of longwave emission leads to heat being trapped within the urban canopy. Urban materials and the urban canopy are characterised by large heat capacities and a large thermal inertia, respectively, leading to storage of energy during the daytime that can be released back into the atmosphere at night (Bohnenstengel et al. 2011). In addition, non-porous urban surfaces promote surface run-off which, combined with reduced vegetation in some cities, limits the cooling effect of evapotranspiration and alters the timing and amplitude of sensible heat fluxes throughout the course of the day (Oke 2002; Bohnenstengel et al. 2011). The urban canopy has a larger thermal inertia than rural vegetated areas and maintains a positive sensible heat flux late into the night due to the thermal inertia offsetting the radiative cooling of the surfaces, contributing to the UHI effect. Anthropogenic heat sources, such as those from heating and air conditioning also contribute (Allen et al. 2011; Sailor 2011; Bohnenstengel et al. 2014).

During the day, urban areas store incoming solar radiation and the urban fabric warms. Once the urban fabric is warmer than the atmosphere, a sensible heat flux starts to warm the atmosphere; the phase of the sensible heat flux is moderated by the heat capacity of the urban fabric. The rural land surface is characterised by a smaller heat capacity and therefore warms up more quickly during the day, leading to a positive sensible heat flux earlier in the day. At night, the small heat capacity of the rural land surface means that less energy is available to offset radiative cooling. In an urban environment, however, the larger heat capacity offsets the radiative cooling for longer which in turn leads to a prolonged positive sensible heat flux and higher air temperatures at night.

The UHI effect is most pronounced during calm and clear nights when local effects dominate the boundary layer structure (Oke 2002). The magnitude of the UHI is often quantified in terms of the urban heat island index (UHII), an estimate of the urban increment on local climate. In the UK, night-time UHIIs up to \(7^\circ \hbox C\) have been observed for London (Watkins et al. 2002; Wilby 2003) and \(5^\circ \hbox C\) for Birmingham (Heaviside et al. 2015). In Manchester, daytime UHIIs of \(3^\circ \hbox C\) and night-time UHIIs of \(5^\circ \hbox C\) for summer days have been observed (Smith et al. 2011). In general, the intensity of urban heat island effect is largest for night-time minimum temperatures, which is important for public health because warm nights limit relief and inhibit recovery from heat stress during the daytime [e.g., Fischer and Schär (2010)].

Average annual frequency of hot days and warm nights for London, Birmingham and Manchester for NCIC observations (black), RCM (blue) and CPM (red). Lighter colours indicate frequency of occurrence of rural hot days/warm nights. See text for hot day and warm night definitions

By definition, the number of rural hot days and warm nights is 1 for the present-day, so is not shown. The number of hot days is correctly reproduced by both models for rural and urban areas to within 1 per year for all cities. The greatest increase in the number of hot days is in the RCM over London, with rural and urban hot days increasing from 1 to 25 and 2 to 29 respectively. In terms of future changes, the number of hot days increases by a similar number for both urban and rural areas in the CPM for all three cities. The increase in the number of hot days is larger over urban areas for London and Manchester, while for Birmingham the increase in the number of rural hot days is larger (+ 1) than urban hot days. For all cities, the number of hot urban and rural days increases more in the RCM than the CPM.

Daytime (top) and night-time (bottom) observed (NCIC, red open squares), CPM (TS1, red squares; future changes, red triangles) and RCM (TS1, black squares; future changes, black triangles) estimates of the UHII

Figure 7 compares observed and UKCP daytime and night-time UHII estimates for Greater London, Birmingham and Greater Manchester. As indicated by Fig. 2 and 3 , the daytime UHII (top) is significantly lower compared to the night-time UHII (bottom). For the present-day daytime over London and Manchester, there is a gradual increase in the UHII with increasing city temperature in the RCM up to \(\approx 1^\circ \hbox C\) for the 99th percentile. Meanwhile, for all cities, the CPM daytime UHII is less than \(1^\circ \hbox C\) for all temperature percentiles, slightly overestimating compared to NCIC-cpm estimates. However, the CPM correctly represents the consistent strength of the urban influence with increasing city temperature. In future, CPM UHII estimates are unchanged for all London and Birmingham city temperature percentiles, but exhibit a slight decrease for the warmest days over Manchester. This is in contrast to the RCM, where, particularly for London and Birmingham, the UHII decreases with increasing city temperature (as much as \(1^\circ \hbox C\) for the hottest days). The urban influence on night-time city temperature extremes (top panels) is markedly different in the RCM compared to the CPM and observations. For the present-day in all three cities, the UHII is overestimated in the RCM for all city temperature percentiles, but this overestimation rapidly increases above the 90th percentile of night-time temperatures. For London, the UHII for the warmest nights is \(4.5^\circ \hbox C\) for London, 3.5 C for Birmingham and \(4^\circ \hbox C\) for Manchester, compared to observed estimates closer to \(0.5^\circ \hbox C\). While the UHII is largest for the hottest nights in the CPM, the increase in UHII with temperature is smaller and more similar in magnitude to observed UHII estimates. In future, the behaviour of the RCM is amplified, with a further increase in the UHII with increasing city temperature for all cities by up to \(1^\circ \hbox C\). While there is a slight reduction in future CPM UHII for the hottest days over Manchester, for both London and Birmingham it is unchanged. These figures provide strong evidence that the RCM is not correctly representing the urban influence, particularly for the warmest nights.

In terms of future changes, all cities show a larger warming around peak temperatures in the CPM compared to the RCM. For Greater London, night-time temperatures (between 18:30 and 07:30 UTC) are projected to increase more in the RCM than the CPM. After sunrise, future changes in urban temperatures increase more in the CPM than the RCM, while the urban influence decreases in the RCM. Interestingly, the magnitude of the future changes in urban influence in the RCM are similar in magnitude to the differences in absolute changes between the CPM and RCM. This suggests that the urban influence in the RCM is dampening the future diurnal cycle, resulting in smaller future increases of daytime temperatures and larger increases in night-time temperatures than in the CPM. For Birmingham, the RCM urban temperatures increase by similar amounts to the CPM, however, the urban signal is reduced for most hours of the day. For Manchester, the difference between the CPM and RCM warming magnitudes is largest, with CPM temperatures warming by as much as \(2^\circ \hbox C\) more than the RCM during the afternoon. Similar behaviour to Greater London in terms of an increased urban heat island at night and cool-island during the early morning is observed. A small decrease in the future urban influence in the CPM is observed mid-morning (09:30 UTC) for London, but for all other hours and cities it is unchanged.

À propos

Début dès Septembre, c haque jeudi, de 18h à 19h, un apéro e...
bottom of page